Air conditioning unit and control



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J. Levne His Att S amuel S. J. LEVINE Filed Jan. 5, 1952 AIRCONDITIONING UNIT AND CONTROL June 28, 1955 United States Patent O AIRCONDITIONING UNIT AND CONTROL Samuel J. Levine, West Orange, N. J.,assiguor to General Electric Company, a corporation of New YorkApplication January 5, 1952, Serial No. 265,138

3 Claims. (Cl. 98--38) This invention relates to air conditioningapparatus and particularly to air conditioning units for officebuildings and the like.

Oliice buildings, for example, may be provided with air conditioningunits supplied with preconditioned air from a central plant but alsoproviding individual control for the offices through the operation ofblowers installed in units in each office for circulating air from thecentral plant and from the room over heat transfer surfaces in the unit.lt is desirable that all the units in the building be under control ofthe central plant so that the entire system may be shut down from thecentral plant. Such shutdowns may be desirable in office buildings, forexample, over the week end; however, it is also desirable thatindividual olices be conditioned although the entire system is not inoperation so that such oices in use when the over-all system is not inoperation may be air conditioned. Accordingly, it is an object of thisinvention to provide an air conditioning system including individuallycontrolled units for rooms of the building and providing ver-all controlfrom the central plant and a selectively controllable arrangement forconditioning individual rooms when the over-all plant is not inoperation.

It is another object of this invention to provide an improved controlsystem for air conditioning units.

It is a further object of this invention to provide an improved controldevice for air conditioning units which is simple in operation andaffords selective control of the unit.

Further objects and advantages of the invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

,In carrying out the objects of this invention, an air conditioning unitof the type comprising a heat transfer a surface and electric motordriven blowers for circulating air over the surface is arranged toreceive air under pressure from a suitable source and is provided with acontrol mechanism for actuating the blower motor upon the occurrence ofa predetermined pressure in the air supply. The control further includesa manually operated element for starting the motor in the absence of airpressure in the supply, this latter control being biased to its neutralposition and being retained in its motor actuating position by alatching mechanism which is released whenever air pressure is restoredin the inlet to the unit. An installation of a plurality of such unitsmay thus be controlled by supplying air under pressure to all of theunits, but individual units may be actuated in the absence of suchpressure by operation of the manual control. A further selective controlis provided so that the motor may be stopped even though the airpressure control is actuated.

For a better understanding of this invention, reference may be had tothe accompanying drawing in which Fig. l is a front elevation, partly insection, of an air conditioning unit embodying this invention; Figs. 2and 3 are end views of the unit of Fig. 1; Fig. 4 is a diagrammatic viewof a plurality of units of the type shown in Fig. l arranged in amultizone installation; Figs. 5 and 6 are enlarged elevation and sideviews, respectively, of the control mechanism employed in the unit ofFig. l; Fig. 7 is a diagrammatic illustration of the electric circuiternployed in the conditioner of Fig. l; and Figs. 8 and 9 are enlargeddetail views, taken on the line 8--8 of Fig. 5, illustrating the twopositions of the manual control switch of the control.

Referring now to the drawing, the air conditioning unit shown in Figs.l, 2 and 3 comprises a casing 16 in the upper portion of which isarranged a heat transfer unit 11 of the finned coil type arranged toreceive heat transfer liquid from a suitable supply through intake anddischarge connections 12 and 13. Air may be circulated over the unit 11by operation of a pair of centrifugal blowers 14 and 15 driven by anelectric motor 16, as indicated by dotted lines in Fig. l. Room air isadmitted to the unit through an opening 17 at the bottom of the casingand flows through a lilter 13 to the blower inlets. Fresh air,preferably conditioned in the central plant, is supplied under pressurethrough an inlet 19 and flows through a series of perforated baffleplates 20 and into an elongated silencer tube 21 from which it tows intothe space below the filter 18, as indicated at 22. Thus the fresh air ismixed with the return air and enters the blower inlets to be circulatedover the heat transfer surface 11.

The unit may be employed either for heating or cooling, suitableequipment being provided in the central plant to supply either heatingor cooling liquid to the unit l1. When the unit is employed for cooling,moisture condensed on the surface of the unit ll flows into a trough 23and then through a drain connection 24 to a collecting funnel 25 underwhich may be placed a conrainer or plumbing connection (not shown). WhenVthe unit is employed for heating, the air supplied under pressure fromthe central plant may be preheated, and when the system is employed forcooling, this air may be precooled thereby removing the major portion ofthe moisture from the fresh air before it is distributed to the units.

The general arrangement of the units in an oliice building, for example,is shown in Fig. 4 where three units 10 have been illustrated arrangedto receive conditioned air under pressure from a central plant 26through a supply duct 27 connected through risers 28 to the inlets 19 ofthe units 10. Each of the units is provided with a control device 29which is arranged to energize the motor 16 whenever air is suppliedunder pressure to the inlet 19 and further, n the event that air is notbeing supplied, these controls are provided with manually adjustablemembers to operate the motors although central plant air is notavailable. The central plant arrangement for supplying heating orcooling fluid to the heat transfer units 11 has not been illustrated inorder to avoid further complication of the drawing. lt will be apparentthat all of the units may be conditioned for operation by supplying airunder pressure through the conduit 27, but that in the event the centralair conditioning system is shut down, as over a week end, individualoiiices may be controlled manually.

The control 29 is provided with a pressure tube or connection 30, shownin Figs. l and 2, which provides communication between the control andthe air supply inlet 19. The details of the control are shown in Figs. 5and 6. The pressure tube 30 is connected to a chamber 32 within anexpansible chamber device 33 which includes a movable diaphragm 34biased to its low pressure position by a spring 35 mounted between thediaphragm and a wall 36 of the device 33. The chamber 32 is formed by awall 37 of the device 33 which is mounted in engagement with the backwall of the casing of the device 29 indicated at 38. An electric switch39 is mounted on a bracket 40 on the wall 36 and includes a switch arm41 arranged in the path of a plunger 42 mounted on the diaphragm 34.When a predetermined pressure prevails in the chamber 32, the plunger 42moves toward and engages the arm 41 and moves it to the left to actuatethe switch. The arm 41 is resiliently urged toward its righthandposition, as illustrated in Fig. 6, by a suitable spring biasing means(not shown), the switch being of the wellknown snap acting type which isbiased to its open position. The switch 39 is connected in the circuitof the motor 16 in the manner illustrated in Fig. 7. The motor 16 may besupplied with current from lines 45 through the switch 39 and a manualswitch 46, shown in its off position. When the switch 46 engages eitherof a pair of terminals 47 and 4S of a reactor 49, the motor is connectedacross the lines 45 upon closing the switch 39. When the switch 46engages the contact 47 the motor is operated at full speed, and when itengages the contact 48 the reactor 49 is placed in series with the motorwhich then runs at reduced speed.

During periods when the majority of the oices in the building areunoccupied and there is no demand for heating, it may happen that insevere winter weather the temperature becomes abnormally low. It isdesirable to prevent reduction of the tempetrature below somepredetermined value and an arrangement is provided so that the fans maybe started when room temperatures fall too low. The heat exchange coilis supplied with warm water at all times, and in order to circulate theair over the coil and prevent too great a reduction in room temperaturea thermostat 50 is provided in the control which engages a contact 51 atthe desired minimum temperature and connects the motor for reduced speedoperation through the reactor 49 even though the switches 39 and 46 areopen. By preventing too great a reduction in temperature in the unusedrooms, the general ambient temperature within the building is preventedfrom falling to too low a value.

From the foregoing, it is readily apparent that all of the units in abuilding such as that illustrated in Fig. 4 may be controlled bysupplying air under pressure through the duct 27; however, during theidle periods of the overall system when air is not being supplied underpressure from outside the room it may be desirable to operate anindividual unit, and for this purpose a manual control having a knob 52is provided to close the switch 39 although the diaphragm 34 is in itsright-hand position and the plunger 42 out of engagement with theswitch. The

knob 52 is secured to a shaft 53 mounted in a bracket 54 secured to thewall 36 of the device 33. A cam 56 is secured to the end of the rod 53and acts as a stop against which the switch arm 41 bears when theplunger42 is disengaged. The cam 56 is eccentric in form, as illustrated inFigs. 8 and 9, its normal position being shown in Fig. 8 andcorresponding to its position as shown in Figs. 5 and 6. The cam 56 isurged to this position by a coil spring 57 having one end engaging thebracket 54 and its other end hooked about a post 5S on the rod .,1,

53. This spring biases the cam 56 to its position as shown in Fig. 8wherein the cam engages the plate 36 at 59. The cam 56 includes anotched or relieved portion 6i) in its periphery remote from the switch53, and when the knob 52 is turned to rotate the rod S3 in a clockwisedirection, as viewed in Fig. 8, the notch 60 engages the switch arm 41and thereby retains the cam 56 in the position shown in Fig. 9, the arm41 being urged against the cam by thebias of the switch arm andpreventing rotation of the shaft 53. Thus the motor may be yactuated byclosing the switch 39 even though air under pressure is not available atthe inlet 19. This enables the occu pant of an individual room tocontrol the circulation of air in that room whether or not the centralplant air supply is in operation. Whenever the central plant is againplaced in operation, the plunger 42 moves the switch arm 41 to the leftout of engagement with the cam, which thereupon is returned to itsposition of Fig. 8 by the biasing spring 57, thereby restoring the unitto automatic control. It will be understood that the switch arm 41 ismoved to its switch closing position by movement of the cam 56 to theposition as shown in Fig. 9 but may be urged beyond the position forinitial closing of the switch by the switch bias upon operation of theplunger 42.

The pressure responsive switch mechanism described hereinbefore isdescribed and claimed in my copending divisional 'application S. N.456,74l tiled September l7, 1954.

From the foregoing, it is readily apparent that a simple and effectivearrangement has-been provided for controlling air conditioning units inmultizone installations while making possible individual control of thcunits when the central plantl automatic control is not in operation,thereby providing a vsystem which is flexible in operation, particularlyfor installations involving a. great many separate zones normallysupplied with fresh air from a common central source.

While a particular embodiment of the invention has been illustratedincluding specific details of structure.y modifications will occur tothose skilled in the art and it is not desired to limit the invention tothe specific structure illustrated, and it is intended to cover `by theappended claims all modications which fall within thc spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. An air conditioning unit for conditioning air in a zone comprising acasing, a heat transfer element in said casing, an air inlet foradmitting zone air to said unit, means for supplying air from outsidesaid zone under pressure to said unit, Ymeans including a blower forcirculating the air supplied to said unit over said element anddischarging said air to said zone, an electric motor for driving saidblower, means including an electric switch for controlling the operationof said motor, manual conA trol means movable to first and secondpositions for actuating said switch in its second position, meansbiasing said manual control to its first position, latching means forretaining said manual control in its second position, and meansresponsive to a predetermined pressure of the air supplied to said unitfrom outside said zone for actuating said switch and for releasing saidlatching means.

2. An air conditioning system for conditioning thc air in a plurality ofzones comprising an air conditioning unit for each of said zones, eachof said units comprising means including a blower for circulating zoneair through said unit and an electric motor for driving the blower.control means for each unit, said control means including a switch forthe motor of the unit and a manually operated member for actuating theswitch, means for biasing said member to its nonoperating position,means for re taining said member in its switch closing position, meansconstituting a common source for supplying preconditioned air underpressure to all of Said units, and means responsive to a predeterminedpressure of the air supplied from Asaid source for actuating saidswitches and for releasing said manual members for return to their nonoperating positions.

3. An air conditioning system for conditioning the air in a plurality ofzones comprising a unit for each of the zones including a heat transfersurface and an velectric motor driven blower for circulating zone airover said surface, an electric switch for each motor driven blower, acommon source for supplying preconditioned air under pressure to all ofsaid units, means on each of said units for actuating the switch thereofin response to a predetermined pressure ofthe air supplied to said unitfrom said source, manual means for actuating the switch of each of saidunits, means dependent upon a pressure of the air supplied from saidsource less than a predetermined value for retaining said manual meansin their actuated positions and for releasing said manual means inresponse to a pressure exceeding said predetermined value.

References Cited in the le of this patent UNITED STATES PATENTS1,969,304 Grooms Aug. 7, 1934

